冀西北怀安地体高级变质表壳岩的锆石年代学研究
发布时间：2018-07-16 23:58
【摘要】：位于华北克拉通中部造山带中北段的怀安地体与内蒙孔兹岩带相接,出露高压麻粒岩和退变榴辉岩等多种高级变质岩,是洞悉华北克拉通古元古代构造演化历史的重要窗口。研究区变质表壳岩包括夕线石榴长英质片麻岩、石榴长英质粒状岩石以及紫苏黑云二长片麻岩。阴极发光图像特征显示研究区样品的锆石主要包括碎屑锆石和变质锆石,其中碎屑锆石具有岩浆结晶环带,而变质锆石为单颗粒或围绕着继承性碎屑锆石边部生长,内部结构均匀,Th/U比值较低。锆石LAICP-MS U-Pb定年结果与前人研究结果综合表明该区变质表壳岩石的碎屑锆石的207Pb/206Pb年龄主要集中在~2040Ma,其原岩形成时代与孔兹岩带变泥质岩石相近,均为~2.0Ga。变质锆石记录其变质时代为1957~1804Ma,结合前人对怀安地区变泥质岩和变基性岩变质作用和年代学研究结果,推测得出1.95~1.92Ga代表了峰期(高压)麻粒岩相变质时代,1.90~1.85Ga代表峰后减压阶段变质时代,而1.85~1.80Ga代表退变质晚期的时代。怀安地区变质岩石可能卷入了阴山陆块、鄂尔多斯陆块以及东部陆块间的先后碰撞造山过程,并持续较长时间(1.95~1.80Ga),最终拼贴为统一的整体。
[Abstract]:The Huai'an terrane located in the central part of the North China Craton orogenic belt is connected with the inner Mongolia Kongzi belt, and many kinds of high grade metamorphic rocks, such as high-pressure granulites and retrograde eclogites, have emerged, which are important windows for understanding the ancient tectonic evolution history of the North China Craton Gu Yuan. Metamorphic crust rocks in the study area include pomegranate feldspar gneiss, pomegranate feldspar granulite and perilla biotite gneiss. The characteristics of catholuminescence images show that the zircons in the study area mainly include clastic zircon and metamorphic zircon, among which the clastic zircon has a magmatic crystallization ring, while the metamorphic zircon is single grain or around the edge of inherited clastic zircon. The ratio of Th / U was lower. The results of zircon LAICP-MS U-Pb dating and previous studies show that the 207Pb / 206Pb age of the detrital zircon of the metamorphic epidermal rocks in this area is mainly concentrated at 2040Ma.The age of origin of the zircon is similar to that of the muddy rocks of the Kongzite belt, and they are all of 2.0 Ga. The metamorphic zircon has a metamorphic age of 1957-1804 Ma. combined with previous studies on metamorphism and chronology of argillite and metamorphic rocks in Huai'an area. It is inferred that 1.95 ~ 1.92Ga represents the peak (high pressure) granulite facies metamorphic epoch (1.90- 1.85Ga) representing the post-peak decompression stage metamorphism, while 1.85- 1.80Ga represents the late retrograde metamorphic period. The metamorphic rocks in Huai'an area may have been involved in the collision orogenic process between the Yinshan block, Ordos block and the eastern continent block, which lasted for a long time (1.951.80Ga) and finally collated into a unified whole.
【作者单位】： 中国地质科学院地质研究所;天津地质矿产研究所;
【基金】：国家自然科学基金项目(41430210、41502181) 中国地质调查局地质大调查项目(DD20160121) 中国地质科学地质研究所基本科研业务费(YYWF201703、J1713)联合资助
【分类号】：P588.3;P597.3
本文编号：2128129
[Abstract]:The Huai'an terrane located in the central part of the North China Craton orogenic belt is connected with the inner Mongolia Kongzi belt, and many kinds of high grade metamorphic rocks, such as high-pressure granulites and retrograde eclogites, have emerged, which are important windows for understanding the ancient tectonic evolution history of the North China Craton Gu Yuan. Metamorphic crust rocks in the study area include pomegranate feldspar gneiss, pomegranate feldspar granulite and perilla biotite gneiss. The characteristics of catholuminescence images show that the zircons in the study area mainly include clastic zircon and metamorphic zircon, among which the clastic zircon has a magmatic crystallization ring, while the metamorphic zircon is single grain or around the edge of inherited clastic zircon. The ratio of Th / U was lower. The results of zircon LAICP-MS U-Pb dating and previous studies show that the 207Pb / 206Pb age of the detrital zircon of the metamorphic epidermal rocks in this area is mainly concentrated at 2040Ma.The age of origin of the zircon is similar to that of the muddy rocks of the Kongzite belt, and they are all of 2.0 Ga. The metamorphic zircon has a metamorphic age of 1957-1804 Ma. combined with previous studies on metamorphism and chronology of argillite and metamorphic rocks in Huai'an area. It is inferred that 1.95 ~ 1.92Ga represents the peak (high pressure) granulite facies metamorphic epoch (1.90- 1.85Ga) representing the post-peak decompression stage metamorphism, while 1.85- 1.80Ga represents the late retrograde metamorphic period. The metamorphic rocks in Huai'an area may have been involved in the collision orogenic process between the Yinshan block, Ordos block and the eastern continent block, which lasted for a long time (1.951.80Ga) and finally collated into a unified whole.
【作者单位】： 中国地质科学院地质研究所;天津地质矿产研究所;
【基金】：国家自然科学基金项目(41430210、41502181) 中国地质调查局地质大调查项目(DD20160121) 中国地质科学地质研究所基本科研业务费(YYWF201703、J1713)联合资助
【分类号】：P588.3;P597.3
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1 张耀华;高新国;宋昌锦;李星云;;辽宁省岩石地球化学研究新进展[J];辽宁地质;1990年03期
，本文编号：2128129
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